of the removal of aquatic plants on fish populations and the 

 deceleration of eutrophication. 



Lake of the Woods. Investigations of the interaction of suck- 

 ers and spawning yellow pickerel were continued in the area 

 of Nestor Falls and Blindfold Dam. Approximately 15,000 

 pounds of suckers were removed while tagging 1 ,200 yellow 

 pickerel. Recaptures of tagged fish will cletermine the rate 

 of angler exploitation and allow comparison of patterns of 

 migration with those of shoal-spawning yellow pickerel. 

 Black crappies have increased in importance to both com- 

 mercial and sport fishermen. Consequently, studies were 

 initiated on the Steven's Bay population, and trap-netting 

 was demonstrated to commercial fishermen as a means of 

 selecting black crappie without affecting populations of 

 sub-adults of other game fish. Routine creel surveys and 

 commercial catch-sampling were continued to determine 

 relative age distribution of the harvest. Important game and 

 commercial fish were collected to determine size-specificity 

 of mercury contamination. 



Rainy Lake. Studies to determine the causes of fluctuations 

 in recruitment rates of yellow pickerel were concentrated 

 in Red Cut Bay and the North and East Arms. Incidence of 

 yellow pickerel fingerlings decreased from 525 to 395 per 

 acre between 1969 and 1970, but the 1970 estimates were 

 greater than those for 1967 and 1968. Experimental netting 

 in the East Arm, in co-operation with the Minnesota Conser- 

 vation Department, indicated an increase in the abundance 

 of older yellow pickerel from 1.6 to 4.2 fish per lift between 

 1966 and 1970. Creel surveys showed that in 1970 anglers 

 harvested an estimated 31,000, 22,000 and 20,000 pounds 

 from the North and East Arms and Red Bay, respectively. The 

 respective catch rates were 0.19, 0.50 and 0.60 fish per 

 angler-hour. The commercial harvest of black crappies in- 

 creased by 310 per cent and, for the first time, exceeded the 

 commercial catch of yellow pickerel. Because of the increas- 

 ing interest in the black crappies shown by commercial 

 fishermen, a survey and trap-net demonstration was carried 

 out during June and July. Besides tagging 1,800 crappies for 

 the investigation of their movements, the demonstration con- 

 firmed the great increase in the black crappie populations. 



Nipissing-Timagami. During the spring, 612 yellow pickerel 

 were tagged and released in Lake Nipissing. To continue 

 this long-term study of the yellow pickerel migration, fifty 

 marked fish were transferred from their home territory to 

 another part of the lake. Creel surveys of resident and non- 

 resident anglers were continued. Undersized sturgeon 

 caught by commercial fishermen were marked and released. 

 On Lake Timagami, 1,775 anglers were interviewed during 

 the winter fishing season; most anglers were fishing for lake 



trout and whitefish, and these species constituted more than 

 90 per cent of the sampled catch. 



Lake Simcoe. More than 2,700 anglers were interviewed 

 during the annual creel survey of the winter fishery; it was 

 found that the average angler fished three hours a day. 

 Spawn collection from yellow pickerel continued on the 

 Talbot River during 1970; 260 quarts of eggs were collected, 

 and 700 adults were tagged and released. Fifty quarts of 

 spawn were collected from 250 fish during a continuing 

 study of lake trout populations. Co-operative studies with 

 the University of Guelph and the Ontario Water Resources 

 Commission were continued. These projects included in- 

 vestigations of the bioecology of smallmouth bass, suckers 

 and smelt in the Pefferlaw River and Lake Simcoe. 



SPECIAL PROJECTS 



Georgian Bay. The study of yellow pickerel was continued 

 in the Moon River area throughout 1970. Trap-netting was 

 carried out during two periods, April 29 to May 22, and 

 August 5 to 28. A total of 3,540 pickerel were captured; 

 2,617 were tagged with monel metal jaw tags and released. 

 No estimates of the spawning population were made in 1970 

 to compare to the estimates of 22,500 pickerel in 1969 and 

 21 ,000 in 1968. 



Tag returns from all sources (not including spring trap- 

 netting) totalled 537 and, as in the past, indicated that the 

 pickerel population becomes widely dispersed after the 

 spawning period. The rate of this dispersion appears to be 

 dependent on the rate of water flow in the river. The 1965 

 year class was dominant in 1970, comprising 47 per cent of 

 the spawning population. 



A creel census showed that 1,029 anglers spent 2,404 

 hours fishing and caught 96 pickerel in the river. The angler 

 index of catch rate dropped from 0.07 to 0.04 mainly as a 

 result of the decreased flow of water in the river. 



Angling success in the Shawanaga Basin appeared to be 

 holding steady or slightly increased from 1969. The trend for 

 pickerel tagged to move further afield after spawning was 

 seen again in 1970. Over 45 per cent of the fish tagged in 

 "inside" waters moved to off-shore waters, presumably to 

 occupy vacant niches formerly inhabited by discrete off- 

 shore populations. 



Commercial landings of pickerel continued to decrease, 

 dropping from 23,483 pounds in 1969 to 15,228 pounds in 

 1970. The reason for this appears to be mainly a decrease in 

 fishing effort. 



This study has succeeded in indicating the importance of 

 the large population of pickerel spawning in the Moon 



24 



